permissions: chkstat does not check for group-writable parent directories or target files in safeOpen()

Summary

A Incorrect Authorization vulnerability in chkstat of SUSE Linux Enterprise Server 12-SP5; openSUSE Leap 15.3, openSUSE Leap 15.4, openSUSE Leap Micro 5.2 did not consider group writable path components, allowing local attackers with access to a group what can write to a location included in the path to a privileged binary to influence path resolution. This issue affects: SUSE Linux Enterprise Server 12-SP5 permissions versions prior to 20170707. openSUSE Leap 15.3 permissions versions prior to 20200127. openSUSE Leap 15.4 permissions versions prior to 20201225. openSUSE Leap Micro 5.2 permissions versions prior to 20181225.